package discord

import (
	"errors"
	"strconv"
	"strings"
)

const clearMax = 20

func init() {
	commands["clear"] = command{
		validate: func(cmd commandInit) bool {
			return isStaff(cmd.message.Member.Roles, cmd.config.StaffRoles)
		},
		run: func(cmd commandInit) error {
			args := strings.Fields(cmd.message.Content)

			var userID string
			if len(cmd.message.Mentions) > 0 {
				userID = cmd.message.Mentions[0].ID
			}

			limitArg := 1
			if userID != "" {
				limitArg = 2
				if len(args) < 2 {
					return errors.New("this command takes needs two arguments with a mention")
				}
			} else if len(args) < 1 {
				return errors.New("this command takes one argument without a mention")
			}

			limit, err := strconv.Atoi(args[limitArg])
			if err != nil {
				return err
			}

			if limit < 0 {
				limit = 0
			} else if limit > clearMax {
				limit = 20
			}

			batch := []string{cmd.message.ID}

			var deleted int
			messages, err := cmd.session.ChannelMessages(cmd.message.ChannelID, 100, cmd.message.ID, "", "")
			for _, msg := range messages {
				if deleted == limit {
					break
				}

				deleteMessage := true
				if userID != "" {
					deleteMessage = msg.Author.ID == userID
				}

				if deleteMessage {
					batch = append(batch, msg.ID)
					deleted++
				}
			}

			return cmd.session.ChannelMessagesBulkDelete(cmd.message.ChannelID, batch)
		},
		help: "Clear messages",
	}
}